# Field Function for Surface Length

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 January 22, 2013, 09:43 Field Function for Surface Length #1 Member   anonymous Join Date: Dec 2012 Posts: 33 Rep Power: 7 Does anyone know if there is a field function for the surface length. I wish to plot pressure coefficient vs surface length on an aerofoil rather than axial distance. Thanks

 January 22, 2013, 10:53 #2 Member   Ryan Coe Join Date: Jun 2010 Location: Albuquerque, NM Posts: 98 Rep Power: 9 You may be able to do this with a combination of vector field functions. Another approach would be to write a field function with a polynomial that gives the location of the surface as a function of the orthogonal coordinates, and then reference that. __________________ Ryan

 January 26, 2013, 07:22 #3 Member   anonymous Join Date: Dec 2012 Posts: 33 Rep Power: 7 what if the surface is just a random collection of points and not a quadratic curve or something like that. is there a way I could use the coordinates of it somehow? Thanks

 January 27, 2013, 11:03 #4 Member   Ryan Coe Join Date: Jun 2010 Location: Albuquerque, NM Posts: 98 Rep Power: 9 What type of airfoil is it? You should be able to come up with a function for the surface based on this. Alternatively, you could just fit a curve to the coordinates. __________________ Ryan

 January 27, 2013, 13:04 #5 Member   anonymous Join Date: Dec 2012 Posts: 33 Rep Power: 7 It is a turbine blade the geometry can be found here: http://www-g.eng.cam.ac.uk/whittle/T106/Start.html I dont think I will be able to use an equation to determine the points. Is there not function that will get the points out of the geometry used in Starccm and make them avaliable. If I export the x and y coordinates of the geometry I can use excel to do it by finding the distance between each point and it gives a rough estimate I was just hoping that star would be able to do this for me thanks

 January 27, 2013, 13:12 #6 Member   Ryan Coe Join Date: Jun 2010 Location: Albuquerque, NM Posts: 98 Rep Power: 9 If it were me, and there were no way of finding the function used to describe the blade geometry, I would export the points and use matlab to fit a function (probably a cubic spline) to the surface. You should be able to export the points by creating a table with the boundary of interest (the airfoil surface). __________________ Ryan

 January 28, 2013, 02:05 #7 Super Moderator   Ryne Whitehill Join Date: Aug 2009 Posts: 313 Rep Power: 12 I've requested this feature from cd-adapco as well. If you have access to fieldview, they do have a method to do it. STAR-CCM+ recently added in a "unwrapper" surface plot that is supposed to take a 3d surface and flatten it to 2d. Not sure if this could be used to flatten the surface out and then do a plot from that.

 January 28, 2013, 08:38 #8 Member   anonymous Join Date: Dec 2012 Posts: 33 Rep Power: 7 I do not have access to fieldview, is it a free program or would I need a licence. Is Unwrapper only in the latest version of Starccm+ as I have 7.04.006 and when I search "unwrapper" in the help file nothing comes up thanks Last edited by badger1; January 28, 2013 at 09:46.

January 28, 2013, 13:15
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Ryne Whitehill
Join Date: Aug 2009
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Quote:
 Originally Posted by badger1 I do not have access to fieldview, is it a free program or would I need a licence. Is Unwrapper only in the latest version of Starccm+ as I have 7.04.006 and when I search "unwrapper" in the help file nothing comes up thanks

Its in 7.04. Not sure if it will do what you want, Ive only glanced at it.

The help file page title is:

Unwrapping, Unrolling and Projecting with Transforms

Its under visualizing solution -> transformations

 Tags field function, pressure, surface length

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